Microwave popcorn popping packages, such as flexible bags, are common. A common feature of such bags is that they are generally made from paper materials that are sufficiently flexible to open or expand conveniently under steam pressure, which forms when a popcorn charge therein is exposed to microwave energy in a microwave oven. Also, the packaging materials are sufficiently flexible to be formed from a sheet into a folded configuration, for example during a continuous bag-construction process. Popcorn popping bags of this type are described, for example, in U.S. Pat. Nos. 5,044,777; 5,081,330; 5,195,829; 6,049,072; and 6,396,036 each of these being incorporated herein by reference. Popcorn popping bags are also described in U.S. Pat. Nos. 4,904,488; 4,973,810; and 4,982,064.
Many microwave popcorn products include a charge of unpopped popcorn kernels, fat/oil (i.e., grease) and flavoring (for example, salt) within the package. During storage or shipment, especially if the environment becomes relatively hot, the material stored within the bag can liquefy and leak through the bag construction. To inhibit such leakage, solid fat/oil products having a relatively high melting or softening temperature (typically at least about 90-115° F.) are used. Additionally or alternatively, some bags are made from expensive materials, such as two ply papers, glassine paper, or papers having a greaseproof coating thereon.
Improvements in microwave popcorn packaging are desired.